Showing Flag Link to Anonymous - Redirects to Registration

I hate hiding user features from anonymous users because each one can lead a user to want to register. I think seeing a 'bookmark this' or 'add to favorites' link as an anonymous user might make me want to register so I can keep an organized list, etc. Can we have an option to at least show the flag links to anonymous users, where as when clicked either redirects to user/register or displays a "please login" message..?

Thanks